Hot Diapers and Cold Fertility

Could plastic diapers be responsible for the reported rise in testicular cancer rates and the decline in male fertility? A team of German researchers thinks so. "Anybody who has ever used the plastic-lined variety knows it can get incredibly hot in there, especially during feverish episodes," says Carl-Joachim Partsch, a pediatrician at the University of Kiel. "They are more leakproof, but that means a lot less ventilation, not to mention more infrequent changes." The heat might wreak havoc on developing testes.

To find out how hot babies get, Partsch and his colleagues measured scrotal skin temperatures of 48 baby boys wearing either disposable diapers or traditional cotton. Not only was it significantly more torrid under the plastic, but scrotal temperatures there often rose as high as body temperatures. "The testicles were designed to be 2 to 4 degrees cooler than the body. If you close that gap in adults for even the length of a sauna, sperm counts drop significantly for up to a week," says Partsch. Kids who grew up wearing disposables may now be feeling the heat.